[Coco] CoCo 3 MMU test for all

[Robert Gault]

Arthur Flexser wrote:

> Roger, the value you get from reading an MMU address depends on exactly HOW you
> read it, I discovered some years back.  This arose when I noticed that the value
> I got from PEEK differed from the value returned by the MON function in ADOS (ML
> monitor).  I traced this to the fact that PEEK used something like LDA 0,X while
> MON used LDA ,X.  The different postbyte affected whether I got $7x (PEEK) vs.
> $3x (MON).  So, I think asking people to PEEK an MMU address and report the
> results will give you a somewhat misleading impression.
> 
> Art

That's interesting. I just tried a test with EDTASM ZBUG with the 
following code.

start lda $ffa0
  ldx #$ffa0
  ldb 0,x      or as an alternate  ldb ,x
  swi
  end

Ran the code and examined the register contents. Both regA and regB were 
$38. However, a PEEK(&HFFA0) from Basic gives $78.

Your on to something Art, but I'm not sure what.